Collaboration Teams - Members share responsibility for posting refined answers to the guided readings - succinct, relevant, clear, and with pictures or a video to compliment.
When contributing to the reading guide, follow these steps: 1) First complete the reading guide on your own from the DNA unit page. 2) Write your response to a question in word and then copy it.Be sure to upload pictures and/or video for each question. 3) Click on the edit button and then go to the appropriate question and paste your answer below it. Sign your contribution with your first name and last initial and TEAM COLOR 4) Save the page by selecting "Save with comment" from the Save dropdown. Enter a comment (e.g. "I answered chp 26 question 3" - Tom S.) then click Save.
Blue
Purple
Green
Pink
Yellow
Orange
Red
1-3
Alecia
Fernanda
Taihlor
4-6
Ashley
Kelly
SamB
7-9
Mr. V Jr.
Brett
10-12
Ryan
Mike
Amy
13-15
Katie
Alina
Dahlia
16-18
Tyler
Chris
19-20
Josh
Megan
Nikki
1. Explain Griffith’s experiment and the concept of transformation in detail.
In 1928 Fredrerick Grifith was studying Streptococcus pneumonia that causes pneumonia in mammals.
Griffith had two strands of the bacterium a pathogenic (disease-causing) one and a nonpathogenic (harmless) strand.
He killed the pathogenic strand with heat and mixed the cells remains with living bacteria of the nonpathogenic strand, some of the living cells became pathogenic.
Transformation is a change in genotype and phenotype due to the assimilation of external DNA by a cell. so in layman's words: a DNA of another cell (bacteria/virus) changes the DNA of the host cell.
2. What did Avery, MacLeod and McCarty contribute to this line of investigation?
They used the Griffith's experiment to figure out that the transforming agent in the bacteria which switched it from harmless to harmful was DNA
3. What is a bacteriophage? is a virus that inflects bacteria also called a phage.
Alecia Seliga 4. Label the diagram below and explain the Hershey Chase experiment.
Sam B. 5. How did Chargraff’s work contribute to understanding the structure of DNA?
He reported that DNA composition varies from one species to another, which accounts for the genetic variation found between different species. He also found a peculiar regularity in the ratios of nucleotide bases within a single species. The DNA composition changes from species to species, but it is consistent within the same species.
-Kelly Sinclair
6. Why was Rosalind’s Franklin’s work essential to the understanding of the structure of DNA? She discovered the structure of a DNA molecule and was inches away from figuring out the double helix until Watson and Crick unfairly gained possession of the slides and made the connection.
this is her photograph from which the double helix was identified.
-ashley a 7. Upload a labeled diagram of DNA and explain what is meant by 5’-3’
The 5'end is attached to a phosphate it is the 5th carbon in the ring. The 3' has a hydrolyze coming from its end. The 5' always begins and the 3' always end, they always go with each other.
Brett S. 8. Why does adenine always pair with thymine and guanine with cytosine in DNA?
First off, adenine and guanine are both purines, nitrogenous bases made of two carbon rings. Cytosine and Thymine are pyrimidines, nitrogenous bases with only one carbon ring. They are half as large as purines. The DNA double helix has a uniform diameter, as shown by Franklin’s image. Pairing purines with purines would make a very wide diameter at that portion and pairing pyrimidines with pyrimidines would make a narrow one in contrast. However, pairing a pyrimidine to a purine makes a consistent diameter. Also, adenine and thymine can make 2 hydrogen bonds, while cytosine and guanine can make three.
DNA base pairing
-Sam V. 9. What is meant by the term that DNA replication is semiconservative?
Basically the idea is that DNA is made of a strand from an old molecule and one strand that is newer.
Brett S. 10. Detail the Meselson and Stahl experiment concerning DNA replication.
Matthew Meselson and Franklin Stahl devised experiments that tested the three hypotheses (Conservative, Semiconservative, and Dispersive Models). Their experiments supported semiconservative model of DNA replication, as predicted by Watson and Crick.
The picture shows Meselson's and Stahl's experiment and how it was performed. It also shows the conclusion from the experiment.
This video explains the semi-conservative model.
-Mike G 11. How is bacterial DNA replication accomplished?
The two strands are separated and then each strand's DNA sequence is recreated by DNA polymerase. This enzyme makes the complementary strand by finding the correct base and bonding it onto the original strand. DNA polymerases can only extend a DNA strand in a 5′ to 3′ direction.
- Ryan H.
12. What are DNA polymerases?
An enzyme that catalyzes the elongation of new DNA at a replication fork by the addition of nucleotides to the existing chain.
13. In your own words, what is meant by the term – DNA is antiparallel in arrangement”?
DNA is anti-parallel in arrangement. This means that the 5'-3' direction of one strand is opposite to the 5'-3' direction of the other strand.
-Dahlia M. 14. Define the following terms: a. Leading strand - the new complementary DNA strand synthesized along the template strand in the mandatory 5' to 3' direction.
b. Lagging strand - a discontinuously synthesized DNA strand that elongates in a direction away from the replication fork.
c. Okazaki fragments - a short segment of DNA synthesized on a template strand during DNA replication. Many Okazaki fragments make up the lagging strand of newly synthesized DNA.
d. DNA ligase - a linking enzyme essential for DNA replication. It also catalyzes the covalent bonding of the 3' end of a new DNA fragment to the 5' end of a growing chain.
e. Primer - a polynucleotide with a free 3' end, bound by complementary base pairing to the template strand, that is elongated during DNA replication. This image shows all of the terms above with the exception of the primer, and indicates for each of the mechanisms relate to one another. - Alina Dyak
15. Upload a video of DNA replication and explain what happens on the 2 antiparallel strands.
1) An enzyme called helicase separates the DNA strands (the space where they separate is called the replication fork). 2) DNA polymerase adds complementary nucleotides to the separated strand of DNA. 3) The DNA polymerase enzyme finishes adding nucleotides and there are two identical DNA molecules.
- Katie Halbruner =]
16. List the functions of the following enzymes: a. Helicase - Enzyme that untwists the double helix at the replication forks, separating the two parental strands and making them available as template strands. b. Single stranded binding protein - Binds to the unpaired DNA strands, stabilizing them until they serve as templates for the synthesis of new complementary strands.
c. Topoisomerase - Helps relieve the strain of the tighter twisting.
d. Primase - Can start an RNA chain from scratch and joins RNA nucleotides together one at a time.
e. DNA Polymerase III - Continuously synthesizes the leading strand and elongates each Okazaki fragment, adding onto both of their primers.
f. DNA Polymerase I - Removes primer from the 5-carbon end of the leading strand and replaces it with DNA, adding on to the adjacent 3-carbon end.
g. DNA Ligase - Joins the 3-carbon end of the DNA that replaces the primer to the rest of the leading strand. Also joins the Okazaki fragments together.
18. What is mismatch repair?
When an enzyme is used to correct mismatched base pairs, the nucleotides sometimes evade proofreading by a DNA polymerase or arise after DNA synthesis is completed. The enzyme is used to fix those errors. 19. Why is there a short section of a cell’s DNA that cannot be repaired or replaced? upload a video or diagram explaining the problem. It is very important that you understand this conceptually.
i found this video a while ago for biotech. it really explains the 5-->3 direction
When contributing to the reading guide, follow these steps:
1) First complete the reading guide on your own from the DNA unit page.
2) Write your response to a question in word and then copy it. Be sure to upload pictures and/or video for each question.
3) Click on the edit button and then go to the appropriate question and paste your answer below it. Sign your contribution with your first name and last initial and TEAM COLOR
4) Save the page by selecting "Save with comment" from the Save dropdown. Enter a comment (e.g. "I answered chp 26 question 3" - Tom S.) then click Save.
Alecia
Fernanda
Taihlor
Ashley
Kelly
SamB
Mr. V Jr.
Brett
Ryan
Mike
Amy
Katie
Alina
Dahlia
Tyler
Chris
Josh
Megan
Nikki
1. Explain Griffith’s experiment and the concept of transformation in detail.
2. What did Avery, MacLeod and McCarty contribute to this line of investigation?
They used the Griffith's experiment to figure out that the transforming agent in
the bacteria which switched it from harmless to harmful was DNA
3. What is a bacteriophage?
is a virus that inflects bacteria also called a phage.
Alecia Seliga
4. Label the diagram below and explain the Hershey Chase experiment.
Sam B.
5. How did Chargraff’s work contribute to understanding the structure of DNA?
He reported that DNA composition varies from one species to another, which accounts for the genetic variation found between different species. He also found a peculiar regularity in the ratios of nucleotide bases within a single species. The DNA composition changes from species to species, but it is consistent within the same species.
-Kelly Sinclair
6. Why was Rosalind’s Franklin’s work essential to the understanding of the structure of DNA?
She discovered the structure of a DNA molecule and was inches away from figuring out the double helix until Watson and Crick unfairly gained possession of the slides and made the connection.
-ashley a
7. Upload a labeled diagram of DNA and explain what is meant by 5’-3’
The 5'end is attached to a phosphate it is the 5th carbon in the ring. The 3' has a hydrolyze coming from its end. The 5' always begins and the 3' always end, they always go with each other.
Brett S.
8. Why does adenine always pair with thymine and guanine with cytosine in DNA?
First off, adenine and guanine are both purines, nitrogenous bases made of two carbon rings. Cytosine and Thymine are pyrimidines, nitrogenous bases with only one carbon ring. They are half as large as purines. The DNA double helix has a uniform diameter, as shown by Franklin’s image. Pairing purines with purines would make a very wide diameter at that portion and pairing pyrimidines with pyrimidines would make a narrow one in contrast. However, pairing a pyrimidine to a purine makes a consistent diameter. Also, adenine and thymine can make 2 hydrogen bonds, while cytosine and guanine can make three.
-Sam V.
9. What is meant by the term that DNA replication is semiconservative?
Basically the idea is that DNA is made of a strand from an old molecule and one strand that is newer.
Brett S.
10. Detail the Meselson and Stahl experiment concerning DNA replication.
Matthew Meselson and Franklin Stahl devised experiments that tested the three hypotheses (Conservative, Semiconservative, and Dispersive Models). Their experiments supported semiconservative model of DNA replication, as predicted by Watson and Crick.
This video explains the semi-conservative model.
-Mike G
11. How is bacterial DNA replication accomplished?
The two strands are separated and then each strand's DNA sequence is recreated by DNA polymerase. This enzyme makes the complementary strand by finding the correct base and bonding it onto the original strand. DNA polymerases can only extend a DNA strand in a 5′ to 3′ direction.
- Ryan H.
12. What are DNA polymerases?
An enzyme that catalyzes the elongation of new DNA at a replication fork by the addition of nucleotides to the existing chain.
13. In your own words, what is meant by the term – DNA is antiparallel in arrangement”?
DNA is anti-parallel in arrangement. This means that the 5'-3' direction of one strand is opposite to the 5'-3' direction of the other strand.
-Dahlia M.
14. Define the following terms:
a. Leading strand - the new complementary DNA strand synthesized along the template strand in the mandatory 5' to 3' direction.
b. Lagging strand - a discontinuously synthesized DNA strand that elongates in a direction away from the replication fork.
c. Okazaki fragments - a short segment of DNA synthesized on a template strand during DNA replication. Many Okazaki fragments make up the lagging strand of newly synthesized DNA.
d. DNA ligase - a linking enzyme essential for DNA replication. It also catalyzes the covalent bonding of the 3' end of a new DNA fragment to the 5' end of a growing chain.
e. Primer - a polynucleotide with a free 3' end, bound by complementary base pairing to the template strand, that is elongated during DNA replication.
- Alina Dyak
15. Upload a video of DNA replication and explain what happens on the 2 antiparallel strands.
1) An enzyme called helicase separates the DNA strands (the space where they separate is called the replication fork).
2) DNA polymerase adds complementary nucleotides to the separated strand of DNA.
3) The DNA polymerase enzyme finishes adding nucleotides and there are two identical DNA molecules.
- Katie Halbruner =]
16. List the functions of the following enzymes:
a. Helicase - Enzyme that untwists the double helix at the replication forks, separating the two parental strands and making them available as template strands.
b. Single stranded binding protein - Binds to the unpaired DNA strands, stabilizing them until they serve as templates for the synthesis of new complementary strands.
c. Topoisomerase - Helps relieve the strain of the tighter twisting.
d. Primase - Can start an RNA chain from scratch and joins RNA nucleotides together one at a time.
e. DNA Polymerase III - Continuously synthesizes the leading strand and elongates each Okazaki fragment, adding onto both of their primers.
f. DNA Polymerase I - Removes primer from the 5-carbon end of the leading strand and replaces it with DNA, adding on to the adjacent 3-carbon end.
g. DNA Ligase - Joins the 3-carbon end of the DNA that replaces the primer to the rest of the leading strand. Also joins the Okazaki fragments together.
18. What is mismatch repair?
When an enzyme is used to correct mismatched base pairs, the nucleotides sometimes evade proofreading by a DNA polymerase or arise after DNA synthesis is completed. The enzyme is used to fix those errors.
19. Why is there a short section of a cell’s DNA that cannot be repaired or replaced? upload a video or diagram explaining the problem. It is very important that you understand this conceptually.
i found this video a while ago for biotech. it really explains the 5-->3 direction
20. What are telom